A contribution analysis and analysis by parts are not necessarily related but CAN be combined. Analysis by parts (ABP) is a method for running an impact when a few different options are present: whenever a sector isn't located in your geography, whenever you want to separate an analysis by it's two key pats (industry sales and labor component), when you need to adjust the spending patterns or when you are working with non-profits.

Are you customizing your spending pattern or using ABP since the electric company is possibly a non-profit? Would the reason for using annual expenditures instead of annual sales be that you don't have sales data? Just expenditures?